ISSN 2042-2695

CEP Discussion Paper No 1404

January 2016

Minimum Wages and Firm Value

Brian Bell Stephen Machin

Abstract How does the value of a firm change in response to a minimum wage hike? The evidence we have to date is not well-suited to answer this question, principally because events that have been studied are not completely unknown to the stock market or have uncertainty associated with them. This paper exploits the announcement of a sizeable change in the minimum wage in the UK that was both totally unanticipated and free of uncertainty. The stock market response of employers of minimum wage workers is examined in an event study setting, looking at minute-by-minute changes surrounding the announcement and at cumulative abnormal returns on a daily basis before and after the announcement. The analysis uncovers significant falls in the stock market value of low wage firms. The size of the fall in value is compared to the fall in profitability in response to the wage cost shock that will be induced by the announcement and is seen to be of a comparable magnitude.

Keywords: Minimum wages, firm value JEL codes: J23; L25

This paper was produced as part of the Centre’s Labour Markets Programme. The Centre for Economic Performance is financed by the Economic and Social Research Council.

We would like to thank Arin Dube, Eric French, Attila Lindner, Alan Manning, participants in the IAB workshop on the German Minimum Wage and in seminars at Oxford, Princeton and Yale for a number of helpful comments and suggestions. Data from the Annual Survey of Hours and Earnings (ASHE) and the Annual Business Survey (ABS) is collected by the Office for National Statistics and supplied by the Secure Data Service at the UK Data Service. The data are Crown Copyright and reproduced with permission of the Controller of HMSO and the Queen's Printer for Scotland. The use of the data in this work does not imply the endorsement of ONS or the Secure Data Service in relation to the interpretation or analysis of the data. This work uses research datasets which may not exactly reproduce National Statistics aggregates.

Brian Bell, Department of Economics, University of Oxford and Centre for Economic Performance, London School of Economics. Stephen Machin, Department of Economics, University College London and Centre for Economic Performance, London School of Economics.

Published by Centre for Economic Performance London School of Economics and Political Science Houghton Street London WC2A 2AE

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means without the prior permission in writing of the publisher nor be issued to the public or circulated in any form other than that in which it is published.

Requests for permission to reproduce any article or part of the Working Paper should be sent to the editor at the above address.

B. Bell and S. Machin, submitted 2016.

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“We strongly support the National Minimum Wage and want to see further real-terms increases in the next Parliament. We accept the recommendations of the Low Pay Commission that the National Minimum Wage should rise to £6.70 this autumn, on course for a Minimum Wage that will be over £8 by the end of the decade.”

Conservative Party Manifesto, April 14th 2015.

“I am today introducing a new national living wage. We will set it to reach £9 an hour by 2020. The new national living wage will be compulsory. Working people aged 25 and over will receive it. It will start next April at the rate of £7.20. The Low Pay Commission will recommend future rises that achieve the Government’s objective of reaching 60 percent of median earnings by 2020.”

Budget Speech, July 8th 2015.

“I’ve talked to several chief executives and been surprised by the impact on their profits. In one [big] company, it would wipe out all of their profits”

Paul Drechsler, CBI President, September 2015.

1. Introduction

Ever since minimum wage floors were first introduced to labour markets around the

world, a perennial research question of high relevance for labour market policy has

been how firms adjust to wage cost increases brought about by increases in the

minimum wage. The first port of call for much of the literature has been to study the

labour demand response of firms, and this has at various points in time generated

research and policy controversies about what minimum wage increases do to

employment or unemployment.1 As evidence of employment losses from minimum

wage hikes has proven elusive in a number of settings, a smaller body of research has

1 Surveying the (mostly US time series) literature that studied data up to the late 1970s, Brown, Gilroy and Kohen (1982) concluded that minimum wages reduced teenage employment, but had less effect on adult employment. The next phase of research were the more micro-based studies of the 1990s, spearheaded by the Card and Krueger (1994) paper on fast food restaurants and Card and Krueger’s (1995) book, which both questioned the earlier findings and found no evidence of disemployment effects. The introduction of the UK National Minimum Wage in April 1999 also generated a number of pieces of research failing to find significant employment effects (see, inter alia, Machin, Manning and Rahman, 2003, Stewart, 2002, 2004, or Dolton, Bondibene and Stops, 2015). In the US there has recently been another revival of research on minimum wage effects, with some focus on geography and differences across state borders. As before this is proving controversial on whether or not minimum wages reduce employment (see, inter alia, Dube, Lester and Reich, 2010 and 2016, Meer and West, 2015, or Neumark, Salas and Wascher, 2014).

2

placed a focus on looking for other margins of firm adjustment. Whilst there are many

such margins, which may differ for firms operating in different sectors, some areas

considered in research have been the scope to pass minimum wages on in terms of

higher prices (e.g. Aaronson and French, 2007; Lemos, 2008), whether firms cut back

on wage increases for other higher paid workers and so reduce wage inequality (e.g.

Lee, 1999; DiNardo, Fortin and Lemieux, 1996; Dickens and Manning, 2004) and on

whether minimum wage increases squeeze firm profitability (e.g. Draca, Machin and

Van Reenen, 2011).

In this paper we study minimum wage effects on firm profitability in a different

way from the direct before/after analysis of changes in accounting profitability that

result from minimum wage changes. Instead we study the impact of the announcement

of a minimum wage change on the stock market value of firms. This approach has been

adopted in a couple of studies before, first by Card and Krueger (1995) who studied

twenty three events in the US between 1987 and 1989 that eventually led to minimum

wage increases in 1990 and 1991, and by Pacheco and Nalker (2006) who undertook

an event study looking at changes in shareholder values following a significant reform

to the youth minimum wage in New Zealand. Neither of these studies delivers very

clear results, primarily because the nature of the ‘events’ that were examined do not

allow for a clean event-study. Such a study would require a completely unexpected

minimum wage change that had no uncertainty attached to its introduction. To take one

example from Card and Krueger, on June 13, 1989 President Bush vetoed a minimum

wage rise. The stock market reaction to this event shows no significant effect on firm

value. But as Card and Krueger note, it is difficult to know whether this veto conveyed

new information to the market, since the White House had promised to veto the bill

3

when it was first passed by the House three months earlier. And if it did contain new

information, how did it change the probability of a minimum wage change?

The event studied in this paper is able to significantly improve upon such

concerns. A completely unanticipated and sizable change in the UK minimum wage

system was announced in the newly elected Conservative government’s emergency

budget that was called after its election to power in May 2015. As the quote from the

budget speech of July 8 2015 reproduced at the top of the first page of this paper

testifies, the Chancellor George Osborne announced that the UK government would

introduce a new National Living Wage (NLW) of £7.20 per hour for workers aged 25

and over. Not only was this announcement from a right of centre government that has

traditionally been against minimum wages, it was also totally unexpected, with other

government ministers and the body which advises the government on minimum wages

(the Low Pay Commission) not knowing that it would occur.2 Thus the major advantage

of our study compared to the other stock market reaction research in this area is that the

announcement we study was completely unanticipated.

The event study approach has been very widely used in finance (see Kothari and

Warner, 2008, or MacKinlay, 1997), but it has also been used by labour economists in

several settings, most notably as a means of studying the effects of unions on firm

performance.3 The seminal paper studying union effects on stock market values was by

Ruback and Zimmerman (1984) whose event study of union representation elections

uncovered evidence of a negative effect of union wins on the equity value of US firms.

Subsequently, Bronars and Deere (1990) uncovered similar effects while Lee and Mas

2 The BBC News reported that day as follows: “In a surprise announcement at the end of his speech, he said workers aged over 25 would be entitled to a "national living wage" from next April, to soften the impact of in-work benefit cuts.” http://www.bbc.co.uk/news/uk-politics-334371153 Another example of event studies in labour economics is Farber and Hallock’s (2009) analysis of the stock market value effects of job loss announcements.

4

(2012) used a much larger sample and wider time window to find a longer run impact

of unions on firm value. These union papers usefully inform the research design we

adopt in our event study, but in the different setting of minimum wage changes.

In this paper, the differential stock market response of employers of minimum

wage workers is compared to that of employers of higher wage workers in an event

study setting looking at minute-by-minute changes surrounding the announcement and

at cumulative abnormal returns in the days before and after the announcement. There is

evidence of significant falls in the stock market value of low wage firms. Within a day

of the budget, firm values were around 1.2 percent lower for the employers of minimum

wage labour and ended up stabilizing around 2 to 3 percent lower after five days. Much

of this adjustment was rapid and had happened within a couple of days. The size of the

fall in firm value is compared to the fall in profitability in response to the wage cost

shock that will be induced by the announcement and is seen to be of a comparable

magnitude.

The remainder of the paper is structured as follows. In Section 2, the relationship

between minimum wages and profitability is first considered, followed by a discussion

of the system of minimum wages that operates in the UK and then how this has altered

following the introduction of the new National Living Wage. Section 3 describes the

data and event study methodology. The results are discussed in Section 4, and Section

5 offers some concluding remarks.

2. Minimum Wages, Profitability and the New National Living Wage

Minimum Wages and Profitability

For a competitive profit maximizing firm employing L workers at wage rate W, using

other factors of production at price R and selling its output at price P, profits are

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maximized at Π(W, R, P). For such a firm, the derivative of the profit function with

respect to the wage rate is ∂Π/∂W = -L(W,R,P), the negative of the demand for labour

and the second derivative is ∂2Π/∂W2 = -∂L/∂W. The introduction of a minimum wage

at a level M, above the prevailing wage W, reduces firm profits by

.

Following Ashenfelter and Smith (1979), this can be approximated as:

(1)

where ΔW = M – W.

The first term on the right-hand side of (1) is the wage bill effect on profits (

) and the second can be thought of as the labour demand ( ) effect

on profits. Equation (1) can be rewritten as:

(2)

where < 0 is the elasticity of labour demand.

Equation (2) offers a means of thinking about the profit response of a firm to a

minimum wage hike. If there is “no behavioural response”, which in this setting means

no impact on labour demand, the second order effect in (2), ( ), is zero. The

fall of profits that would result from the imposition of a minimum wage M is equal to

the proportionate change in the wage multiplied by the wage bill.

If adjustment can occur, then the labour demand effect in the second term is

non-zero. This can offset the profit loss to the extent that firms can substitute away from

low-wage workers into other factors (e.g. capital). One interesting question is the speed

at which such adjustment could occur. In the event study setting of the empirical work

in this paper, this is particularly interesting when one attempts to gauge the size of the

P)R,Π(M,P)R,Π(W,ΔΠ

2W)(W

L

2

1 W LΔΠ

WL- 2W)(W

L

2

1

2

W

ΔW

2

η

W

ΔWWLΔΠ

W

L

L

Wη

2

W

ΔW

2

η

6

profit reduction from a change in market value (which is the present discounted value

of firm profits).4

Other models focus on the particular mode of adjustment to the wage cost shock

from a higher minimum wage. In Aaronson and French (2007), for example, firms have

constant marginal costs and thus a horizontal supply curve and so, irrespective of the

nature of competition in the product market, the minimum wage increase is passed on

entirely to consumers in the form of higher prices. In putty-clay models (like Aaronson,

French and Sorkin, 2015) the same is true.5 Some other alternatives to adjusting prices

that allow the firm to negate the negative impact on profits include compression of the

internal wage structure, efficiency wages/productivity improvements and conventional

labour demand responses (see, for example, Hirsch, Kaufman and Zelenska, 2015).

Equation (2) also usefully illustrates the inverse relationship between a firm’s

initial wage and the profit change. It shows that, the lower the initial wage, then the

greater the fall in profits associated with the imposition of a minimum wage. This logic

underpins what we do in our empirical work where we focus on the stock market

response of employers of minimum wage workers in an event study setting. The means

by which we define firms that employ minimum wage workers is considered in Section

3 of the paper where we also describe the data that we use.

Minimum Wage Setting in the UK

A National Minimum Wage (NMW) was introduced to the UK labour market

in April 1999. Prior to that, minimum wages did not play a role in wage determination

4 See also Abowd’s (1989) classic study of union wage increases and firm performance. Abowd estimates a version of equation (2) examining the effects of unanticipated increases in the wage bill (which he defines as union wealth) on the present discounted value of profits as reflected in changes in stock market values ( or shareholder wealth). Interestingly, the findings are unable to reject the simple no behavioural response model where the second order effect is zero. 5 See also Sorkin (2015) who emphasises the distinction between modes of adjustment in the short and long run.

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as the system that used to operate (the Wages Councils who set sectoral minima in low

wage sectors, only covering about 10 percent of UK workers) had been abolished by

the Conservative government in 1993 (Dickens, Machin and Manning, 1999).

The rate at which the National Minimum Wage was introduced was determined

by a body set up by the Labour government which was elected in May 1997. The Low

Pay Commission (LPC) was instituted as an advisory body by the National Minimum

Wage Act of 1998. The LPC has nine Commissioners, three of which are from business,

three of which are from employee representation groups, and three are members who

are independent from the social partners. These last three are the Chair and two

academics who are experts in labour economics and industrial relations.

The LPC remit is set by the government each spring, with a main focus on

coming up with evidence-based recommendations on the main adult minimum wage

rate and the associated age-specific minima. The LPC assesses evidence from a wide

range of sources (e.g. academic research, site visits, an annual consultation procedure

with oral evidence taken from a wide range of stakeholders). It then makes

recommendations in a report submitted to government in February, to which the

government responds on acceptance or rejection of the recommendations, and then if

accepted (as the main adult rate always has been since introduction) the NMW is

uprated on October 1st.6

Figure 1 shows the rates from 1999 to 2015. In April 1999 the National

Minimum Wage was first introduced at a rate of £3.60 per hour for workers aged over

21, together with a youth development rate at £3.00 per hour for 18-21 year olds.

Through time more rates have been introduced: in 2004 a minimum wage for 16-17

6 For more detail on the functioning of the LPC see Brown (2002), Butcher (2012) and Metcalf (1999, 2002).

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year olds was introduced, and an apprentice minimum wage in 2010. Also in 2010 the

adult rate was extended to 21 year olds, so that by 2015 there were four rates in place:

the adult minimum (now for those aged 21 and over) which had reached £6.70 by

October 2015; the youth development rate for 18-20 year olds of £5.30; the rate for 16-

17 year olds of £3.87; and the apprentice rate of £3.30.7

In many quarters, the operation of the LPC has been deemed a success. The

Institute of Government’s 2010 polling of 159 members of the Political Studies

Association rated the NMW as the most successful government policy of the previous

thirty years.8 This reflects the evidence-based approach leading to little in the way of

employment losses from the NMW, and the independence of the LPC in being able to

make its deliberations largely free from political intervention.

The New National Living Wage

After being in a coalition government with the Liberal Democrats as the UK

government in power between May 2010 and 2015, the Conservative party was elected

outright in the May 2015 election. It called an emergency budget for July 8 2015 and

in this budget the Chancellor George Osborne made the completely unexpected

announcement of introducing a new National Living Wage that would raise the NMW

for age 25 year olds and older workers by 50 pence from April 2016. The main reason

for this was to offset the tax credit cuts that the Chancellor introduced in the budget in

his strong programme of austerity cuts.

7 The UK government has almost always accepted the LPC’s recommendations on rates. This has always been true for the recommendations adult, development and 16-17 year old rates. The recommendation on apprentice rates has twice been met with a government instituted change: first in 2011 when the LPC recommended a freeze of the rate but government intervened to increase it by 5 pence; then more markedly in 2015 when the LPC recommended raising the rate by 7 pence from £2.73 to £2.80 as the business secretary pushed the rate a further 50 pence up to £3.30. 8 See: http://www.bbc.co.uk/news/uk-politics-11896971.

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From a political economy perspective, this is a striking and radical intervention.

It comes from a political party that has traditionally been strongly against minimum

wages and, indeed, which strongly opposed the introduction of the NMW in the first

place. The very poor real wage performance of most workers in the UK labour market

since 2008 (when median real wages have fallen by around 10 percent, but such falls

are seen across most of the wage distribution as well) has altered this standpoint to some

extent.9 It is true that all of the main UK political parties (including the Conservatives)

have recognised that minimum wages are both popular amongst the general public and

that they can play a role in raising wages (and by association living standards).10

The surprise of the budget announcement and the size of the wage shock is what

we exploit in our event study of the impact on the stock market value of firms.11 The

50 pence NLW supplement on adult minimum wages came as a complete surprise to

the market. The Chancellor also introduced a target level for the adult minimum wage

of £9 per hour to be reached by 2020. This was also news to the stock market, as the

Conservative Manifesto before the May 2015 election (quoted at the start of the paper)

was clear in the aspiration of reaching £8 per hour by that date.

The introduction of the NLW also alters the role of the LPC in its future

deliberations, as it now has a target to work to. In practical terms the government

intervention has also effectively introduced a new age band into the structure of

minimum wages that operate for low wage workers in the UK. This is shown in Table

9 See Blundell, Crawford and Jin (2014) and Gregg, Machin and Fernandez-Salgado (2014) for more detail on the nature of real wage falls in the UK labour market. 10 On the popularity of the UK minimum wage, a 2014 Gallup poll reported that 66 percent of those polled were in favour of increasing the minimum wage. 11 In addition to being unanticipated, we noted earlier that a key additional requirement for a successful event study, particularly when trying to evaluate the size of any estimated effect, is that there be no uncertainty over the introduction of the new minimum wage. The announcement considered in this paper satisfies that requirement because the 1998 National Minimum Wage Act gives Government Ministers the power to set the minimum wage without reference to the LPC. The Government confirmed in writing to the LPC on Budget Day that such an order would be made.

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2 where the new structure of minimum wage rates that will apply from 2016 is

compared to those of 2014 and 2015.

The new NLW also offers an ‘experiment’ not made possible by previous

increases in the minimum wage coming from the LPC recommendations. In due course,

it will be interesting to study the employment and other economic effects of this big

increase, of 10.8 percent compared to the £6.50 rate at the time of the announcement,

or of 7.5 percent compared to the already accepted LPC rate of £6.70 that was made

effective after the budget in October 2015. By 2020, the targeted minimum wage of £9

is 12.5 percent higher than the £8 level that had previously been suggested.

As a result of the minimum wage changes and 2020 target, the number of

workers in the UK labour market who are covered by the minimum is expected to rise

significantly. Figure 2 shows actual coverage from 1999 to 2014 and expected coverage

from 2015 onwards (defined as the number of workers paid at or below the relevant

minimum and up to 5 pence above). There is a significant increase resulting from the

change. In 2015 before the change the number of covered workers had risen gradually

to reach 1.6 million by 2015. Afterwards, due to the new NLW of April 2016 and the

2020 target, there is a sharp increase, straight away jumping to over 2.5 million, and

reaching 3.8 million by 2020.

3. Data and Modelling Approach

Data

The equity price data come from Datastream and Bloomberg. The principal sample

frame is made up of the constituents of the FTSE All-Share Index. This index comprises

eligible companies listed on the London Stock Exchange main market that pass

screenings for liquidity and investability. The index captures 98 percent of the UK’s

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market capitalization. There are 643 constituents of the index, with a mean (median)

market capitalization of £3.1bn (£599mn).

We exclude from our analysis all investment trusts and private equity funds,

giving a final sample of 442 firms. We have daily prices, total returns and volume. We

also extract daily data on market capitalization, dividend yield and the price-book ratio.

Trade-level data for the announcement date are taken from Bloomberg. These data

contain the price, volume and exact time of every trade during the official trading day

(8am to 4.30pm). We use this data to compute the volume-weighted price for each stock

by minute of the trading day.

Treatment Firms

To estimate the effect of the increase of the minimum wage on firm market

values, we need to construct a sample of firms that are exposed to the treatment. We

first follow the approach of Draca, Machin and Van Reenen (2011) by using accounting

information on the average wage of the firm to sort firms. The annual accounts report

the total wage and salary costs for the firm and the average number of employees. This

gives us a measure of the average annual wage per employee. Since the new minimum

wage is set at £7.20, a worker who is employed full-year full-time would earn £14,976.

We therefore identify the quoted firms in our sample who are expected to be

affected by the minimum wage announcement on the basis of their average wage per

employee being less than £15,000 per year. The strength of this identification approach

depends on the extent to which minimum wage workers are concentrated in firms at the

lower end of the wage distribution. Unfortunately, firms are not required to report any

information on the distribution of wages within the firm, only the average wage.

To therefore assess the usefulness of the approach we adopt, we study a different

data source looking at the segregation of wages across firms in the UK using the 2013

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cross-section of the Annual Survey of Hours and Earnings (ASHE) and the Annual

Business Survey (ABS). These are matched worker-firm level data that allows us to

look at within-firm wage distributions and explore the association between average

wages and the intensity of low-wage workers. We have a sample of 62,594 workers

(and 7,795 firms) employed in the private sector who can be matched to firm-level data

that includes the average wage per employee.

We follow the Low Pay Commission procedure of defining a minimum wage

worker as any worker who receives an hourly wage (excluding overtime) that is up to

five pence above the minimum wage effective at the time of the survey (April 2013).

Overall, 6.2 percent of our sample are minimum wage workers. This is very similar to

the 7 percent figure reported for all private sector workers in the UK in the 2014 Low

Pay Commission report (page 22). Our final restriction is that firms must employ at

least 100 workers and have an average wage of at least £5,000. These two sample

restrictions reduce our sample to 59,535 workers (and 5,853 firms), but the share of

minimum-wage jobs remains at 6.2 percent.

In Figure 3, we plot the proportion of minimum-wage workers in a firm against

the firm’s average annual wage for those firms with an average wage below £30,000

(40,046 workers in 3,684 firms). We split the sample into vigntiles of the average wage,

with a sample of 186 firms in each bin. There is clearly a strong decline in the proportion

of minimum-wage workers as the average wage rises. Only for those bins to the left of

the £15,000 cutoff are at least 10 percent of the workforce on the minimum wage. On

average, 21 percent of workers in firms with an average wage of less than £15,000 are

minimum-wage workers. Alternatively, one can note that 75 percent of minimum-wage

workers work in firms that have average annual wages of less than £15,000.

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These figures underestimate the impact of the minimum wage on our equity

sample, because they reflect the average share of minimum-wage workers across all

industries. Our equity sample however is heavily focused on two particular industries

(see the list of firms and their sectors in the Appendix), namely non-specialised Retail

Trade (47190) and Beverage Serving activities (56302). As Table 2 shows, if we further

restrict the ASHE/ABS sample to only include these two industries, we have a sample

of 2,924 workers (and 84 firms). In these industries, 30.3 percent of workers in firms

with an average wage of less than £15,000 are minimum-wage workers.

We also require that the firm has a majority of its employees based in the UK.

Some of the low average wage firms are predominantly operating in low-wage

economies, but have chosen to list on the London stock exchange. Clearly these firms

are not affected by the UK minimum wage. Our final sample of NMW firms comprises

the twenty companies that are listed (grouped by sector) in the Appendix. Together,

these 20 firms employ over 600,000 workers.

Event Study Method

We follow the by now standard approach in the finance literature to estimate

the effect of the minimum wage change on a firm’s equity value. We compute the

abnormal return as the difference between a stock’s actual return and the expected

return. For firm i at time t, the abnormal return is simply:

|

where is the actual realized return and | is the expected return, with

denoting the information set at time t.

We consider a number of alternative specifications for | . Perhaps the

most common approach is to use the Capital Asset Pricing Model (CAPM) to estimate

the sensitivity of the ith firm’s return to a market index (i.e. is the market return) and

14

use the predicted values as an estimate of the expected return. This approach is adopted

by Ruback and Zimmerman (1984), Card and Krueger (1995) and Lee and Mas (2012).

To implement this, we estimate a daily return model of the form:

where is the return on the equal-weighted FTSE All Share index. The market model

is estimated over a twelve-month period up to the 15th April 2015, which is 60 days

prior to the minimum wage announcement. The abnormal return from the CAPM model

is then simply:

It is well-known however that the cross-section of stock returns can be predicted

by more than simply the market return (Fama and French, 1992). We therefore also

present results using a four-factor model for expected returns that includes the market

return, a size return based on market capitalization, a value return based on dividend

yield and a momentum return.12

One further factor that could affect our results is that firms with sizeable

minimum wage exposure tend to be heavily distributed in certain industries that employ

more low wage workers such as retail, hotels, restaurants and bars. Evidence suggests

that stock returns have an important industry component (Moskowitz and Grinblatt,

1999; Fama and French, 1997) and if, by chance, these particular industries experienced

abnormal returns relative to the market since the announcement date for reasons

unrelated to the minimum wage, we would ascribe those returns to the minimum wage

12 For the four-factor model, we estimate each factor return by allocating all stocks in the FTSE All-Share index into (a) a large, medium and small-cap portfolio based on the 30th and 70th percentile rank on the previous trading day, (b) a high, medium and low dividend yield portfolio based on the 30th and 70th percentile rank on the previous trading day and (c) a high, medium and low momentum portfolio based on the 30th and 70th percentile rank on the previous trading day of returns over the period 126-21 days prior to the ranking. We then generate daily factor returns by taking the difference between the two extreme portfolios for each factor. See Dube, Kaplan and Naidu (2011) for another example of an event study using factor models.

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announcement. The expected return definition used above will not account for this. We

therefore also construct two-digit SIC industry returns (excluding the minimum wage

firms themselves) and use these as our measure of expected returns. So in our main

results we consider estimates of abnormal returns from three alternative models: (1) the

CAPM, (2) a four-factor model and (3) a 2-digit industry model.

4. Results

In this section we discuss the results of our analysis. We begin by presenting minute-

by-minute evidence to demonstrate the strong reaction of our minimum wage sample

to the exact announcement time of the minimum wage increase. We then examine the

subsequent daily abnormal returns. Finally we present evidence from a regression

model that suggests a significant ability of the market to isolate minimum wage firms

from other, arguably similar, firms.

Intra-day Announcement Effect

The Chancellor of the Exchequer began the Budget statement at 12.33 on July

8th. At 13.35, he announced the decision to raise the minimum wage, one hour and two

minutes into the speech. He concluded the speech four minutes later, at 13.39. We can

therefore exploit the intra-day price change in our sample to examine whether there was

any difference in returns between the NMW firms and the non-NMW firms prior to the

announcement time (13.35) and whether there was a subsequent divergence. We have

minute-by-minute data on the trade price and volume traded of each stock. We present

results for both the equal-weighted index of NMW firms and a value-weighted index

that accounts for the very different trading volumes that are present in the intra-day

data.

16

To motivate the analysis, Figure 4 shows minute-by-minute share price moves

for three low wage firms from the market open on budget day to 24 hours after the

NLW announcement. The three firms are a retail firm Home Retail Group, a pub JD

Wetherspoon and a hospitality firm The Restaurant Group. In all three cases, there is a

marked dramatic drop in their share prices at the precise time that the minimum wage

announcement was made. The initial drop within half an hour was of the order of 2-3

percent and was broadly sustained for the rest of the trading day. On market opening

at 8:00 AM the next day, the pub JD Wetherspoon took another hit dropping a further

2 percent, presumably as the market had more time overnight to absorb and assess the

information contained in the announcement.

Analysis of the whole sample of NMW firms is provided in Table 3. Panel A

gives the minute-by-minute cumulative abnormal returns (CAR (X, Y)) for the NMW

stocks from the time of announcement (X = A) over the subsequent Y minutes. In Panel

B we report the pre-announcement returns. The abnormal returns are calculated for a

market model (i.e. adjusting returns for the overall market return over the same period)

and for the two-digit industry model. The first two columns of results use equal-

weighting, whilst the final two columns are value-weighted. Figure 5 displays the

cumulative raw returns to the NMW and non-NMW stocks from the beginning of the

trading day to 24-hours after the announcement, while Figure 6 shows the equal-

weighted abnormal return for the NMW stocks. The 95 percent confidence interval

around the mean abnormal return is also shown for the latter.

For the pre-announcement effects, there are two key points. First, there was

essentially no trend in the market in the hours prior to the Budget and no significant

difference between the NMW and non-NMW stocks. Second, all of the Budget

announcements prior to the minimum wage announcement had very little effect on

17

market prices and almost no effect on the relative performance of the two groups of

firms.

From 13.35 onward, the picture is very different. There was a sharp fall in the

price of NMW stocks. One hour on from the announcement, the NMW firms on average

experienced a fall of as much as 69bp relative to the market on an equal-weighted basis,

and 176bp on a value-weighted basis.13 Although these effects weaken as the trading

day finished, all observations on the average abnormal returns of the NMW firms are

negative from the announcement time. Moreover, on market opening the day after

budget day, the gap significantly widens again as Figures 5 and 6 make very clear, so

that 24 hours after the NLW announcement the fall in cumulative abnormal returns is

around 1.2 percent. Overall, we take this as strong evidence that the decline in NMW

prices relative to non-NMW prices occurred as a direct result of the minimum wage

announcement and was not as a consequence of other Budget changes (or indeed other

events in the market).

Before we move on to consider the results on the evolution of daily cumulative

returns, it is interesting to look at the minute-by-minute pattern for the day before (7th

July) and up to minimum wage announcement. We do this so as to both undertake a

placebo-type experiment and to see whether there was any general pre-announcement

trend in the NMW abnormal returns. Figure 7 plots the equal-weighted abnormal

returns for the NMW firms, together with 95 percent confidence intervals. The Figure

makes it very clear that at no point were the pre-announcement day abnormal returns

significantly different from zero (relative to the same time of day as the announcement

on the 8th).

13 Note that the smaller equal-weighted as compared to value-weighted returns simply reflect the fact that stocks that were traded less actively had more positive returns than the more actively traded stocks.

18

Cumulative Abnormal Returns

Having demonstrated an intra-day response to the minimum wage

announcement, we now turn to consider daily cumulative abnormal returns from the

announcement day onward. We compute these equal-weighted cumulative abnormal

returns from day X to day Y as (CAR(X, Y) =∑ ARitt Yt X . So for example denoting X=A

as announcement time, CAR(A, 10) measures the cumulative abnormal return on the

NMW stocks for the post-announcement part of Budget day and the first ten trading

days from then. We use three expected return models: (1) the CAPM model, (2) a 4-

factor model and (3) a two-digit industry-matched model.

Table 4 presents the key results for the mean CARs, whilst Figure 8 plots the

CAR (using the industry-matched model for returns) with associated 95 percent

confidence intervals for the 10 days either side of the announcement. Panel A of the

table gives post-announcement returns for a one-, two-, three-, four-, five-, and ten-day

horizon, while Panel B reports the pre-announcement returns for corresponding

horizons in the pre-Budget period. We study daily returns for a 10-day window since

the announcement is clear and public, so we would expect the market to re-price

reasonably fast. Longer horizons are increasingly likely to bring in other events not

related to the NLW that may shift abnormal returns differentially for treatment and

control firms. We do however comment below on estimated CARs for up to three

months after the announcement.

The decline over the announcement day and the following day, CAR(A, 1), is

in the range -1.4 to -1.7 percent, depending on the expected return model we adopt.

Over the five-day period, the decline is between -2.1 percent and -3.0 percent. At this

point, the decline seems to have stabilized, since there is at most an additional 20bp

decline over the subsequent five days. This suggests that the market reacted quickly to

19

the announcement, with around one-half to three-quarters of the adjustment occurring

by the end of the first-day after the Budget. All the estimated negative cumulative

returns are statistically significant at the 5 percent level or better.

Panel B shows weak evidence that the NMW firms outperformed over the pre-

announcement period, though none of the CARs are statistically significant. This

suggests that if anything the results may slightly underestimate the effect of the

minimum wage announcement, since we know that stocks tend to have momentum over

these holding-period horizons (see Jegadeesh and Titman, 1993).

As already noted, other events may start to impact the estimated CARs as the

time window is extended further. That said, when we did widen the window and

estimate a twenty- and sixty-day CAR, we obtained estimates (and associated standard

errors) of -2.919 (1.884) and -3.968 (3.755) for the industry-matched model. The

significantly reduced precision of these estimates is not at all surprising, but the

magnitude does show that the significant fall experienced within the first few days of

the announcement appears to be permanent.

Possible Small Sample Issues

As with other event studies, small sample issues may lead to possible biases.

The first concerns the relatively small number of firms in the treatment group and the

volatility of returns for some of the less traded firms. To consider this, we have therefore

also estimated CARs for the median firm at each horizon and by trimming the two

highest and lowest CARs within the sample of twenty firms in the same way as the

mean regressions in Table 4. The results for the five-day horizon are reported in Table

A1 in the Appendix. All these alternative approaches continue to show significantly

negative effects – though the point estimates are somewhat less negative in general. We

also find that 15 of the 20 firms in the NMW portfolio have a negative abnormal return

20

five-days after the announcement (regardless of expected return model). Using 18

months of pre-announcement data, we find that for this sample of 20 firms, such a large

number of negative returns across the portfolio lies outside the 95 percent confidence

interval.

A second issue is that the distribution of cumulative abnormal returns may not

be normally distributed as assumed. We therefore also undertook a non-parametric

analysis where we estimated CARs in an estimation window that predates the NLW

announcement. As one example of this, we estimated five-day industry-matched CARs

based on daily data from September 2013 through April 2015 and considered their

distributions. The 5th percentile CAR was -1.59 and the 95th percentile CAR was +1.73;

the 1st percentile was -2.67 and the 99th percentile +2.34. We can then ask, given how

this specific portfolio of stocks moved over the last two years, how likely is it that over

a five-day window they would decline by the size of our estimated CAR of -3.047. This

has an empirical p-value of 0.002. In general, these empirical confidence intervals

broadly matched the standard confidence intervals used in Table 4.

Regression Based Analysis

In a final analysis of the returns data, we examine the cross-section of all post-

announcement abnormal returns for the full sample of 442 firms. We are interested

primarily here in whether there is evidence to suggest that the market was able to

accurately identify the firms most at risk from the minimum wage rise and whether our

identification approach to minimum-wage firms is plausible given the market response.

Table 5 reports some regression results for this cross-section of returns for the

five-days following the announcement (results that prove qualitatively similar for ten-

day returns are given in Appendix Table A2). We use the CAPM model to estimate

expected returns, but the results are robust to using any of the alternative return models

21

considered before. In column (1) we simply report the coefficient on a dummy if the

firm was in our NMW sample. The coefficient of -2.131 on this dummy is of course

equal to the mean abnormal return after five-days reported in the first column of Table

4. In column (2) we additionally add controls for 2-digit industry, market-capitalization

size quintile and pre-announcement returns. These controls marginally increase the size

of the estimated negative effect for the NMW firms to -2.331.

In column (3) we consider whether the negative cumulative returns for the

NMW sample are merely a result of a more general decline for lower-wage firms. Since

we use the cutoff of less than £15,000 average wage to identify the NMW firms, we

consider whether firms in the £15-20k, £20-25k and £25-30k average wage bracket

experienced any similar pattern (with £30k+ being the omitted group). There is no

evidence to support this idea, suggesting that the market focused closely on the lowest-

wage firms.

In column (4) we divide the NMW sample into two equal-sized groups of 10

firms. One group, NMW High π Impact, are those firms in which the mechanical

percentage reduction in pretax profits from a 4 percent rise in the wage bill (the

estimated effect of the minimum wage hike for the average firm in our sample – see

below) is above the median, and the second group, NMW Low π Impact, are those for

which it is below the median. We would expect the cumulative abnormal returns to be

more negative for the NMW High π Impact group, and this is exactly what we find.

Indeed one cannot reject that the entire abnormal return decline is a result of the declines

for these firms, though the point estimate is negative for the NMW Low π Impact firms

as well.

Table 6 further refines the analysis, looking at a minimum wage exposure

variable that we were able to match to our firms from the ASHE and ABS data described

22

above. This measures the actual proportion of workers paid the National Minimum

Wage in April 2013, and is defined for 275 of the original 442 firms (and 19,441

workers). We lose firms for two key reasons. First, some firms are listed on the London

Stock Exchange but the holding company is not UK-domiciled. These firms do not

appear in the ABS as the sampling frame is only UK-registered companies. We lose 99

companies as a result. Second, as the ASHE wage data is only a 1 percent sample, some

firms do not have any workers recorded in the data. For each firm that we can match,

we compute the minimum wage exposure (NMW Exposure) by calculating the

percentage of workers that had an hourly wage no more than 5p higher than the October

2012 minimum wage rate of £6.19. The advantage of this measure is that it captures the

full range of minimum-wage exposure for all firms, rather than just focusing on 20

firms.

Columns (1) and (2) of Table 6 report the regression of 5-day abnormal returns

after the national living wage announcement on this exposure variable (Table A3 in the

Appendix reports results for 10-day returns). It should be noted that the results in Table

5 are replicated almost exactly if we re-estimated on the reduced sample of 275 firms.

The exposure variable is significantly negative, so that firms with a higher proportion

of minimum wage workers experience a larger decline in value following the

announcement. Taking the coefficient in column (2), the results suggest that firms with

a 10 percentage point higher fraction of the workforce employed on the minimum wage

experienced a 62bp additional decline in stock price following the announcement.

We also define a dummy variable equal to 1 if the firm is one of the 20 firms

with the largest estimated minimum wage exposure. Columns (3) and (4) show

23

regression results for this dummy variable.14 The estimates are very similar to those in

Table 5, which suggests that the results we have established are robust to reasonable

alternative definitions of the particular constituents of the portfolio of NMW stocks.

Impact on Profitability

Consider the sample of firms that have an average wage of less than £15,000 in

the matched worker-firm data discussed in Section 3. We noted above that for the two

principal industries in our equity sample, 30 percent of workers in these firms are

minimum-wage workers. To evaluate the impact of a minimum-wage hike for these

firms, we start by noting that for the low-wage firms in these industries, minimum-wage

workers account for 21 percent of the wage bill. This of course is lower than their share

of employment since they are by definition the lowest paid workers in the firm. So the

simple direct effect of increasing the minimum wage by 10 percent for these workers

would generate a wage bill rise of 2.1 percent.

But this calculation ignores two additional effects. First, all workers currently

above the minimum wage but who would fall below the new minimum wage, must have

their wages raised to at least the new minimum. 27 percent of workers are in this group,

and to raise their wages at least to the new minimum adds an additional 1.3 percent to

the wage bill, giving an overall increase of 3.4 percent. Second, it is usually assumed

that workers seek to protect their relativities following a minimum wage increase. A

simple method of capturing this is to assume that workers on the old minimum wage

get the full 10 percent increase and that all workers within 20 percent of the old

minimum receive some wage increase on a smoothly-sliding scale that maintains wage

rank order, places everyone at least at the new minimum and tapers the minimum wage

14 This sample of 20 firms therefore differs somewhat from that used in the results in Table 5 which are based on the average wage in the firm (from the company annual report).

24

effect to vanish for all workers with wages already above 10 percent of the new

minimum. This gives a total wage bill increase of 4.1 percent. We would argue that this

suggests a fairly tight bound on the wage bill effect of the increase, for the average firm

in our sample, to be between 3 and 4 percent.

How reasonable is this calculation? Perhaps the best evidence comes directly

from one of the firms in our NMW sample. Next plc (a large clothes retailer) released

its half-yearly report in September 2015. They provided a detailed calculation of the

impact of the NLW on their wage bill. By 2020, the firm estimated that the wage bill

would be £27m higher as a result of paying the NLW (including the associated costs of

maintaining relativities) on a total wage bill of £720m, or 3.8 percent.

Table 7 calibrates the impact of this scale of wage bill shock on firm profits. We

use data from the last three Annual Reports of the 20 firms in our equity sample. All

these reports predate the minimum wage announcement. We normalize sales to be 100

and compute the average for each firm of the wage bill and pre-tax profits. The figures

in column (1) report the baseline. On average, the wage bill is equal to 18.6 percent of

total sales and the pre-tax profit equals 6.0 percent. This is a relatively low profit

margin, though is common for firms in these sectors. We focus on pre-tax profits

because we assume that any hit to the wage bill feeds through all the profit measures

e.g. firms cannot for example alter their financing costs to offset the wage bill rise. With

a real interest rate of 3 percent, a pre-tax profit of 6 gives a present value of 200.

Now consider a rise in the minimum wage of 10 percent (the average rise over

the next four years) that raises the wage bill by 4 percent (column (2)). Assuming no

offsetting effects, pre-tax profits fall by 12 percent. If this rise in the wage bill is

permanent (i.e. no subsequent reduction in the minimum wage) and there are no

offsetting effects, the present value of the firm drops by 12.4 percent to 175.2.

25

Alternatively, suppose that the firm takes the hit in full for five years but then

successfully generates fully offsetting effects elsewhere on the income statement. Then

firm value declines by 1.6 percent.

We can also evaluate the size of the response in terms of variable exposure to

the minimum wage. We reported in Table 6, that a firm with a 10 percent higher share

of minimum-wage workers experienced an additional estimated 62bp fall in value. In

the final column of Table 7, we show that a firm employing 40 percent minimum wages

workers (10 percentage points above the baseline), would experience a decline in

present value of 17 percent. Again assuming full offset in the medium-run, the drop in

firm value is predicted to be 2.3 percent, 70bp more than for the baseline firm. This

very closely matches the estimate from our empirical analysis.

Whilst these numbers are inevitably somewhat back-of-the-envelope, they do

suggest that the size of the effect we have estimated in our empirical work (a 2-3 percent

decline) is consistent with the market believing that firms will be able to significantly

offset the costs of the minimum wage, at least in the medium term. Crucially, our

estimates are inconsistent with there being a large, permanent effect on firm profits

where employers are unable to adjust to respond to the additional wage costs induced

by the minimum wage increase.

How will firms achieve this offset in practice? Again, we can look at corporate

reports issued since the announcement that have commented on the NLW introduction.

At the time of writing, four firms in our sample have released reports that discuss the

NLW. To varying degrees, they all expect to be able to significantly mitigate the effects

of the rise in the wage bill. Factors mentioned include increasing prices, raising

productivity and increasing cost efficiency. Interestingly, none of the firms mentioned

an employment response. For example, Next plc (whose half-yearly report we have

26

referred to above) say that a 1 percent increase in product price over the next four years

would completely offset their additional wage costs from the National Living Wage.

5. Conclusions

Based on a stock market event study, the empirical research presented in this paper

describes what happened to the market value of firms employing minimum wage

workers when a completely unexpected announcement of raising the minimum wage

occurred. The setting is an emergency budget that was called promptly after the new

election of a right of centre government in the UK. The UK Chancellor of the Exchequer

made a surprise announcement on budget day (July 8 2015) that he would introduce a

new National Living Wage some 11 percent higher than the prevailing National

Minimum Wage for workers aged 25 and above.

The impact of the announcement is studied both intra-day and for up to ten days

either side of the announcement. Unlike the work on stock market responses to

minimum wages in other settings, where the unanticipated nature and certainty of the

announced rises are much less precise than in our setting, we find there to be a strong

and lasting impact on stock market values. The size of this reduction in firm value

resulting from the NLW announcement is compared to the fall in profitability in

response to the wage cost shock that will be induced by the announcement and is seen

to be of a comparable magnitude, assuming that firms can adjust over time. Thus the

announcement of NLW introduction seems to have had the impact of significantly

reducing the expected profits of UK firms when it is to be implemented in April 2016.

27

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30

Figure 1: UK National Minimum Wages, 1999-2015

01

23

45

67

£ P

er

Hou

r

Ap

r 1

999

Oct

20

00

Oct

20

01

Oct

20

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20

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20

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20

13

Oct

20

14

Oct

20

15

National Minimum Wage Rates, 1999-2015

Adult Rate Youth Development Rate16-17 year Old Rate Apprentice Rate

Notes: From Low Pay Commission annual reports.

31

Figure 2: Actual and Estimated Minimum Wage Coverage, 1999-2020

0

.5

1

1.5

2

2.5

3

3.5

4

Num

ber

(in

Mill

ions

) P

aid

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199

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National Minimum Wage Coverage

Notes: Low Pay Commission calculations from Annual Survey of Hours and Earnings (ASHE) from 1999 to 2014 and from 2015 onwards using wage forecasts from ASHE 2014. Paid at or below the minimum is based upon the Low Pay Commission procedure of defining a minimum-wage worker as any worker who receives an hourly wage (excluding overtime) that is up to five pence above the minimum wage effective at the time of the survey

32

Figure 3: Minimum Wage Shares and Firm Average Wages

Average Wage = £15,000

0

.05

.1

.15

.2

.25

.3

Sh

are

of M

inim

um

Wag

e W

ork

ers

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Average Wage Vigntile

Minimum Wage Worker Share and Average Firm Wages

Notes: The y-axis shows the proportion of minimum-wage workers in the firm. The x-axis shows the average annual wage in the firm divided into bins for 5 percentiles from lowest (left) to highest (right) – a total of 20 bins for annual wages from £5,000 to £30,000. Derived from matched worker-firm data (40,046 workers in 3,684 firms) from the 2013 Annual Survey of Hours and Earnings (ASHE) and the Annual Business Survey (ABS).

33

Figure 4: Examples of Share Price Movements of NMW Firms

NLW Announcement at 13-35

Open Close/Open

-5-4

-3-2

-10

1In

dex

= 0

at M

ark

et O

pen

on B

ud

get D

ay

8-00 13-35 16-30/8-00 13-34

Time of Day

Home Retail Group

NLW Announcement at 13-35

Open Close/Open

-5-4

-3-2

-10

1In

dex

= 0

at M

ark

et O

pen

on B

ud

get D

ay

8-00 13-35 16-30/8-00 13-34

Time of Day

JD Wetherspoon

NLW Announcement at 13-35

Open Close/Open

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1In

dex

= 0

at M

ark

et O

pen

on B

ud

get D

ay

8-00 13-35 16-30/8-00 13-34

Time of Day

The Restaurant Group

34

Figure 5: Returns On Budget Day and 24 Hours After The NLW Announcement

NLW Announcement at 13-35

Open Close/Open

-1.4

-1.2

-1-.

8-.

6-.

4-.

20

.2.4

Ind

ex =

0 a

t Ma

rket

Ope

n on

Bu

dge

t Da

y

8-00 13-35 16-30/8-00 13-34

NMW Firms Non-NMW Firms

Time of Day

35

Figure 6: Gap in Returns On Budget Day and 24 Hours After The NLW Announcement

NLW Announcement at 13-35

Open Close/Open

-2.2

-1.8

-1.4

-1-.

6-.

2.2

.61

1.4

Ind

ex =

0 a

t NLW

An

noun

cem

en

t Tim

e

8-00 13-35 16-30/8-00 13-34

NMW/Non-NMW Gap 95% CI

Time of Day

Notes: Based on 442 FTSE All-Share Index quoted firms, comprising 20 NMW firms and 422 Non-NMW firms. The 20 NMW firms are listed in the Appendix.

36

Figure 7: Placebo Test – Day Before Budget Day, July 7 2015

NLW Placebo Announcement at 13-35

Open Close/Open

-2.2

-1.8

-1.4

-1-.

6-.

2.2

.61

1.4

Ind

ex =

0 a

t NLW

An

noun

cem

en

t Tim

e

8-00 13-35 16-30/8-00 13-34

NMW/Non-NMW Gap 95% CI

Time of Day

Notes: Based on 442 FTSE All-Share Index quoted firms, comprising 20 NMW firms and 422 Non-NMW firms. The 20 NMW firms are listed in the Appendix.

37

Figure 8: Daily Cumulative Abnormal Returns

NLW Announcement at 13-35 on July 8-7

-6-5

-4-3

-2-1

01

2C

umu

lativ

e A

bnor

ma

l Re

turn

s

-10 -5 0 5 10

Cumulative Abnormal Return, CAR(A, Y) 95% CI

Days Relative to NLW Announcement A (0 = Close July 8)

Notes: Based on 442 FTSE All-Share Index quoted firms, comprising 20 NMW firms and 422 Non-NMW firms. The 20 NMW firms are listed in the Appendix. Cumulative abnormal returns for the NMW firms are measured using a 2-digit industry return index as the expected return measure. The announcement date (Day 0) was budget day on July 8 2015, with the announcement A occurring at 13-35, two-thirds of the way through the trading day.

38

TABLE 1. AGE VARIATIONS IN MINIMUM WAGES, 2014-2016

Uprating Date October 2014 October 2015 April 2016

Decision Process and Date

Government Accepted Low Pay

Commission Recommendations in

March 2014

Government Accepted Low Pay

Commission Recommendations in

March 2015

Chancellor Introduced National

Living Wage For 25+ Workers in July

2015 Budget

Adult NMW, Age 21+ 6.50 6.70 Adult NMW, Age 21-24 6.70 Adult NLW, Age 25+ 7.20 Youth NMW, Age 18-20 5.13 5.30 5.30 Youth NMW, Age 16-17 3.79 3.87 3.87

TABLE 2. MINIMUM WAGE SHARES AND FIRM AVERAGE WAGES

All Firms Firms With Average Wage<£15,000

Number of Firms

Mean Wage

Share of Minimum

Wage Workers

Number of Firms

Mean Wage Share of Minimum

Wage Workers

All 3684 16943 0.096 1259 11878 0.210NMW Firms 84 14046 0.247 58 11736 0.303 Non-NMW Firms 3600 17170 0.093 1201 11894 0.206

Notes: Derived from matched worker-firm data (40,046 workers in 3,684 firms) from the 2013 Annual Survey of Hours and Earnings (ASHE) and the Annual Business Survey (ABS). The NMW firms are those in the two particular industries that dominate our equity sample, non-specialised Retail Trade and Beverage Serving activities.

Notes: From Low Pay Commission annual reports and July 2015 budget.

39

TABLE 3. ESTIMATES OF INTRA-DAY CUMULATIVE ABNORMAL RETURNS

Equal-Weighted Value-Weighted

(1) Market Model

(2) Industry- Matched Model

(3) Market Model

(4) Industry- Matched Model

Panel A: NMW Firms – Post-Announcement

CAR(A,20) -0.342** (0.131)

-0.271* (0.125)

-1.419** (0.551)

-1.246** (0.537)

CAR(A,60) -0.694** (0.238)

-0.638** (0.242)

-1.759** (0.681)

-1.564** (0.662)

CAR(A,120) -0.469 (0.288)

-0.575 (0.312)

-1.495** (0.447)

-1.408** (0.425)

CAR(A, Market Close) -0.280 (0.323)

-0.262 (0.334)

-0.996* (0.495)

-0.815 (0.491)

Panel B: NMW Firms – Pre-Announcement

CAR(-20,A) -0.040 (0.045)

-0.121* (0.054)

0.034 (0.038)

-0.080 (0.040)

CAR(Budget Start, A) -0.023 (0.089)

-0.054 (0.093)

0.149 (0.086)

0.086 (0.075)

CAR(Market Open, A) -0.183 (0.368)

0.038 (0.363)

-0.164 (0.159)

0.298 (0.139)

Notes: CAR(A, Y) denotes the cumulative abnormal return from announcement t time A (13:35) to minute Y relative to the announcement time. There are 20 firms in the NMW sample. Panel A reports results for the post-announcement period and Panel B reports results for the pre-announcement period. The market closed 175 minutes after the announcement, it opened 334 minutes before the announcement and the budget began 62 minutes before the announcement. The cumulative abnormal return for each firm is equal-weighted in columns (1) and (2) and weighted by their share of the total value of all trades in NMW stocks over the relevant period in columns (3) and (4). ** denotes significance at 1 percent level; * denotes significance at 5 percent level.

40

TABLE 4. ESTIMATES OF MEAN DAILY CUMULATIVE ABNORMAL RETURNS

(1) CAPM Model

(2) 4-Factor Model

(3) Industry-Matched

Model

Panel A: NMW Firms – Post-Announcement

CAR(A,1) -1.428** (0.523)

-1.516** (0.542)

-1.693** (0.564)

CAR(A,2) -1.799** -1.967** -2.465** (0.608) (0.620) (0.709)

CAR(A,3) -1.661** -1.823** -2.553** (0.617) (0.612) (0.660)

CAR(A,4) -1.533* -1.639* -2.774** (0.656) (0.656) (0.773)

CAR(A,5) -2.131* (0.917)

-2.231* (0.910)

-3.047** (1.235)

CAR(A,10) -2.268* (1.128)

-2.464* (1.165)

-3.241** (1.370)

Panel B: NMW Firms – Pre-Announcement

CAR(-1,A) -0.327 (0.512)

-0.357 (0.533)

-0.368 (0.520)

CAR(-5,A) 0.500 (0.800)

0.402 (0.805)

0.767 (0.832)

CAR(-10,A) 1.647 (0.934)

1.523 (0.963)

0.768 (0.904)

Notes: CAR(A, Y) denotes the cumulative abnormal return from announcement time on July 8th (A) to close on day Y, where Y is relative to 8th July. There are 20 firms in the NMW sample. Panel A reports results for the post-announcement period and Panel B reports results for the pre-announcement period. ** denotes significance at 1 percent level; * denotes significance at 5 percent level.

41

TABLE 5. REGRESSION ESTIMATES OF FIVE-DAY ABNORMAL RETURNS

(1) (2) (3) (4)

NMW -2.131* (0.894)

-2.331* (0.943)

-2.266* (1.032)

NMW High π Impact -3.318* (1.607)

NMW Low π Impact -1.071 (1.044)

Average Wage £15-20k -0.196 (0.909)

-0.146 (0.912)

Average Wage £20-25k 0.262 (0.568)

0.295 (0.565)

Average Wage £25-30k 0.291 (0.899)

0.297 (0.902)

Sample Size 442 442 442 4422-Digit Industry N Y Y Y5-Day Prior Return N Y Y Y Size Quintiles N Y Y Y

Notes: The dependent variable is the five-day cumulative abnormal return, CAR(A,5), using the CAPM model. NMW are our sample of 20 firms with average wage less than £15,000. NMW High π Impact are the 10 NMW firms for which a 4 percent rise in the wage bill would generate the largest percentage decline in pre-tax profits. NMW Low π Impact are the other ten firms in the NMW sample. Robust standard errors in parentheses. We also control for foreign exposure with a dummy equal to one if the majority of firm employment (or sales) is outside the UK. ** denotes significance at 1 percent level; * denotes significance at 5 percent level.

42

TABLE 6. REGRESSION ESTIMATES OF FIVE-DAY ABNORMAL RETURN

USING ACTUAL EXPOSURE

(1) (2) (3) (4)

NMW Exposure

NMW Sample

Sample Size 2-Digit Industry 5-Day Prior Return Size Quintiles

-5.020* (2.422)

275 N N N

-6.208* (2.964)

275 Y Y Y

-2.123* (0.920)

275 N N N

-2.185* (1.041)

275 Y Y Y

Notes: The dependent variable is the five-day excess return using the CAPM model. NMW Exposure is the percentage of workers in the firm that earn within 5p on the National Minimum Wage in the ASHE sample for the firm. NMW Sample is a dummy variable equal to 1 if the firm is one of the 20 firms with the largest value for NMW Exposure and where the measure of exposure is based on at least 30 observations in ASHE. We also control for foreign exposure with a dummy equal to one if the majority of firm employment (or sales) is outside the UK. Robust standard errors in parentheses. ** denotes significance at 1 percent level; * denotes significance at 5 percent level.

43

TABLE 7. THE NATIONAL LIVING WAGE EFFECT ON FIRM PROFITS

Baseline Firm 10 Percent Increase in Minimum Wage

(30 Percent Minimum Wage Workers)

10 Percent Increase in Minimum Wage

(40 Percent Minimum Wage Workers)

Sales 100 100 100Wage Bill 18.6 19.3 19.6 Other Costs 53.9 53.9 53.9 Gross Profit 27.5 26.8 26.5 Operating Profit 8.7 8.0 7.7 Pre-Tax Profit 6.0 5.3 5.0

Present Value of Pre-Tax Profits 200 175.2 165.9

Percent Decline in Firm Value (Permanent)

-12.4 -17.1

Decline in Firm Value (Hit to 2020, Thereafter No Effect)

-1.6 -2.3

Notes: Column 2 assumes a 3 percent real interest rate, 4 percent rise in wage bill (resulting from a 10 percent minimum wage increase, assuming 30 percent of workers are NMW workers). Column 3 assumes a 5.5 percent rise in the wage bill (resulting from a 10 percent minimum wage increase, assuming 40 percent of workers are NMW workers). If, rather a 10 percent increase, the minimum wage increase is gradated as a path of 7 percent, 9 percent, 11 percent and 12 percent increases to get to the £9.00 per hour target in 2020 the calculation turns out to be almost identical.

44

Appendix

List of National Minimum Wage Firms By Sector

Bars and Restaurants

Greene King plc J D Wetherspoon plc Marston’s plc Mitchells & Butlers plc The Restaurant Group plc

Retail

Apparel Next plc

Broadline B&M European Value Retail Debenhams plc Marks and Spencer Group plc Home Retail Group plc

Food McColl’s Retail Group plc WM Morrison Supermarkets plc Greggs plc

Home Improvement Dunelm Group plc

Specialty Card Factory plc Game Digital plc Poundland Group plc WH Smith plc

Services

Business Support Mitie Group plc

Recreational Cineworld Group plc

45

Additional Tables

TABLE A1. ALTERNATIVE ESTIMATES OF DAILY CUMULATIVE ABNORMAL

RETURNS

(1) CAPM Model

(2) 4-Factor Model

(3) Industry-matched

Model

Mean -2.131* (0.917)

-2.231* (0.910)

-3.047** (1.235)

Median -1.148* (0.563)

-1.358** (0.510)

-2.213* (1.125)

Trimmed Mean -1.343** (0.394)

-1.392** (0.395)

-2.444** (0.658)

Negative Return Count 15* (5, 14)

15* (5, 14)

15* (4, 14)

Notes: Estimates are for the five-day cumulative abnormal return, CAR(A,5) for the NMW stocks. The trimmed mean excludes the two largest and two smallest returns. Negative Return Count is the number of stocks (out of 20) that have a negative five-day CAR (with the empirical 95 percent confidence interval below). ** denotes significance at 1 percent level; * denotes significance at 5 percent level.

46

TABLE A2. REGRESSION ESTIMATES OF TEN-DAY ABNORMAL RETURNS

(1) (2) (3) (4)

NMW -2.268* (1.101)

-2.540* (1.136)

-2.676* (1.220)

NMW High π Impact -4.089* (1.765)

NMW Low π Impact -1.080 (1.383)

Average Wage £15-20k -0.321 (1.012)

-0.259 (1.107)

Average Wage £20-25k -0.934 (0.751)

-0.894 (0.749)

Average Wage £25-30k 0.615 (1.115)

0.619 (1.117)

Sample Size 442 442 442 4422-Digit Industry N Y Y Y10-Day Prior Return N Y Y YSize Quintiles N Y Y Y

Notes: The dependent variable is the ten-day cumulative abnormal return, CAR(A,10), using the CAPM model. NMW are our sample of 20 firms with average wage less than £15,000. NMW High π Impact are the 10 NMW firms for which a 4 percent rise in the wage bill would generate the largest percentage decline in pre-tax profits. NMW Low π Impact are the other ten firms in the NMW sample. We also control for foreign exposure with a dummy equal to one if the majority of firm employment (or sales) is outside the UK. Robust standard errors in parentheses. ** denotes significance at 1 percent level; * denotes significance at 5 percent level.

47

TABLE A3. REGRESSION ESTIMATES OF TEN-DAY ABNORMAL RETURN

USING ACTUAL EXPOSURE

(1) (2) (3) (4)

NMW Exposure

NMW Sample

Sample Size 2-Digit Industry 10-Day Prior Return Size Quintiles

-6.850* (2.920)

275 N N N

-7.816* (3.319)

275 Y Y Y

-2.537* (1.025)

275 N N N

-2.428* (1.149)

275 Y Y Y

Notes: The dependent variable is the ten-day excess return using the CAPM model. NMW Exposure is the percentage of workers in the firm that earn within 5p on the National Minimum Wage in the ASHE sample for the firm. NMW Sample is a dummy variable equal to 1 if the firm is one of the 20 firms with the largest value for NMW Exposure and where the measure of exposure is based on at least 30 observations in ASHE. We also control for foreign exposure with a dummy equal to one if the majority of firm employment (or sales) is outside the UK. Robust standard errors in parentheses. ** denotes significance at 1 percent level; * denotes significance at 5 percent level.

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